Attentional attraction of receptive fields can explain spatial and temporal effects of attention

A multitude of attentional effects were found at both the neural and behavioural levels of perception; however, the nature of the attentional mechanism is an unsettled issue. It is typically assumed that the fundamental impact of attention is enhancement of neuronal responses, but some attentional effects are difficult to explain by such gain modulations. Here we offer a different view: We suggest that the most fundamental impact of attention is the attraction (shift) of receptive fields towards the attended location. We further show, both conceptually and by model simulations, that this attraction of receptive fields can explain a diverse range of attentional effects, spatial as well as temporal, linking physiological measurements at the unit level with psychophysical observations (e.g., enhanced contrast sensitivity, enhanced spatial resolution, the Mexican-hat profile of attention, prolonged perceived duration, prior entry, degraded temporal resolution).     

Decomposition of warning effects in Parkinson's disease

ABSTRACT

Neutral warning signals speed voluntary reactions by reducing temporal uncertainty and by triggering a brief burst of arousal. We attempted to isolate the phasic arousal mechanism in people with Parkinson's disease (PD) using a clock display to minimize temporal uncertainty. In this condition, the speeding of responses in a color-discrimination task by an accessory stimulus was the fully equivalent to the effect in age-matched control subjects. This indicates preserved phasic arousal in PD. Temporal preparation based on warning cues also appeared to be normal. By contrast, in a condition with high temporal uncertainty, the accessory stimulus (an air puff to the foot) impaired accuracy for the patients but not the neurologically normal subjects. The data are consistent with the view that PD disrupts internal but not external control of alertness.     

Working Memory for Item and Temporal Information in Younger and Older Adults

ABSTRACT

Two experiments examined age differences in mechanisms hypothesized to affect activation of item and temporal information in working memory. Activation levels were inferred from the ability to reject n-back lures matching items in different temporal positions. Information with the least decay had a performance advantage over less recent information, but was susceptible to the same temporal context errors found in all adjacent-to-target lure positions. Lures most distant from the current item showed a performance rebound. The pattern of increased magnitudes of age effects at adjacent-to-target positions indicated a reduction in older adults' working memory for temporal context information above and beyond item memory declines. Results overall support the emphasis on context information as a critical factor in working memory and cognitive aging.     

Temporal order perception of auditory stimuli is selectively modified by tonal and non-tonal language environments

The close relationship between temporal perception and speech processing is well established. The present study focused on the specific question whether the speech environment could influence temporal order perception in subjects whose language backgrounds are distinctively different, i.e., Chinese (tonal language) vs. Polish (non-tonal language). Temporal order thresholds were measured for both monaurally presented clicks and binaurally presented tone pairs. Whereas the click experiment showed similar order thresholds for the two language groups, the experiment with tone pairs resulted in different observations: while Chinese demonstrated better performance in discriminating the temporal order of two “close frequency” tone pairs (600 Hz and 1200 Hz), Polish subjects showed a reversed pattern, i.e., better performance for “distant frequency” tone pairs (400 Hz and 3000 Hz). These results indicate on the one hand a common temporal mechanism for perceiving the order of two monaurally presented stimuli, and on the other hand neuronal plasticity for perceiving the order of frequency-related auditory stimuli. We conclude that the auditory brain is modified with respect to temporal processing by long-term exposure to a tonal or a non-tonal language. As a consequence of such an exposure different cognitive modes of operation (analytic vs. holistic) are selected: the analytic mode is adopted for “distant frequency” tone pairs in Chinese and for “close frequency” tone pairs in Polish subjects, whereas the holistic mode is selected for “close frequency” tone pairs in Chinese and for “distant frequency” tone pairs in Polish subjects, reflecting a double dissociation of function.     

A hierarchical model of operational anticipation windows in driving an automobile

Driving an automobile is an example of a goal-directed activity with high complexity in which different behavioral elements have to be integrated and brought into a sequential order. On the basis of the reafference principle and experimental results on temporal perception and cognitive control, we propose a hierarchical model of driving behavior, which can also be adapted to other goal-directed activities. Driving is conceived of as being controlled by anticipatory neuronal programs; if these programs are disrupted by unpredictable stimuli, which require an instantaneous reaction, behavioral control returns after completion of the reactive mode to the anticipatory mode of driving. In the model different levels of anticipation windows are distinguished which, however, are interconnected, in a bi-directional way: (a) Strategic level with a representation of the driving activity from the beginning to reaching the final goal; (b) Segmented tactical level with the sequence of necessary milestones to reach the goal; (c) Maneuver level where actions like passing another car or keeping a lane are controlled; (d) Short-term integration level of a few seconds which allows immediate anticipations; and (e) Synchronization level for sensorimotor control and complexity reduction within neuronal assemblies. A flow diagram schematically describes different driving situations stressing the anticipatory mode of control. In a pilot experiment with 20 subjects using a virtual driving situation in a car simulator predictions of the model could be verified, i.e., subjects showed a significant preference for the anticipatory mode of driving.     

Movement characteristics support a role for dead reckoning in organizing exploratory behavior

Rat exploration is an organized series of trips. Each exploratory trip involves an outward tour from the refuge followed by a return to the refuge. A tour consists of a sequence of progressions with variable direction and speed concatenated by stops, whereas the return consists of a single direct progression. We have argued that processing self-movement information generated on the tour allows a rat to plot the return to the refuge. This claim has been supported by observing consistent differences between tour and return segments independent of ambient cue availability; however, this distinction was based on differences in movement characteristics derived from multiple progressions and stops on the tour and the single progression on the return. The present study examines movement characteristics of the tour and return progressions under novel-dark and light conditions. Three novel characteristics of progressions were identified: (1) linear speeds and path curvature of exploratory trips are negatively correlated, (2) tour progression maximum linear speed and temporal pacing varies as a function of travel distance, and (3) return progression movement characteristics are qualitatively different from tour progressions of comparable length. These observations support a role for dead reckoning in organizing exploratory behavior.     

Modulation of brain activity during phonological familiarization

We measured brain activity in 12 adults for the repetition of auditorily presented words and nonwords, before and after repeated exposure to their phonological form. The nonword phoneme combinations were either of high (HF) or low (LF) phonotactic frequency. After familiarization, we observed, for both word and nonword conditions, decreased activation in the left posterior superior temporal gyrus, in the bilateral temporal pole and middle temporal gyri. At the same time, interaction analysis showed that the magnitude of decrease of activity in bilateral posterior temporal lobe was significantly smaller for LF nonwords, relative to words and HF nonwords. Decrease of activity in this area also correlated with the size of behavioral familiarization effects for LF nonwords. The results show that the posterior superior temporal gyrus plays a fundamental role during phonological learning. Its relationship to sublexical and lexical phonological processing as well as to phonological short-term memory is discussed.     

Time course of brain activation during graphemic/phonologic processing in reading: an ERP study

The present study sought to investigate the time course of brain activation during grapheme-to-phoneme conversion and phonologic processing of legal Italian syllables. To this goal, we monitored a group of right-handed native Italian volunteers performing a phonologic decision task (same/different judgments). ERPs were recorded from 28 scalp sites during silent reading. Analysis of ERP latency showed faster responses to same syllables than to different ones as early as 105 ms at left temporal electrode site and 160 ms at frontal sites. The first effect of phonologic/graphemic incongruity on the amplitude of ERPs was observed at lateral occipital/posterior temporal sites (N185), where physiologic responses were enhanced to incongruous syllables.